Nick Clegg has distanced himself from an official government document stating any European Union action to punish Russia for its invasion of Crimea should exempt the City of London.

The deputy prime minister, who attended a meeting of the National Security Council (NSC) on Monday where officials outlined the thinking in the document, said no economic and diplomatic action against Russia should be ruled out. But he said a military response was "not on the cards".

The secret document carried by an official in Downing Street. Photograph: Steve Back

Clegg, who was speaking at the Royal United Services Institute (RUSI), said: "Whilst military action – British military participation – is clearly not on the cards, I want to be really clear that Russia will face a range of diplomatic and political and economic consequences if it carries on on its current course.

"We are absolutely not ruling out now the kind of options that we will look at in order to make it very, very clear to President Putin and the Russian Federation that there will be very real consequences. So there is no predetermined limit on the kinds of measures we will look at, envisage, entertain in order to safeguard the territorial integrity of Ukraine."

Douglas Alexander, the shadow foreign secretary, described the document as a serious blunder. "We have seen reports overnight of what was a serious blunder at a serious time by the government revealing what seemed to be a discord between what was being recommended to ministers in private and what was being said in public.

"I hope today, when the foreign secretary speaks to members of parliament in the House of Commons, he will be clear that Britain along with its allies in the international community have not yet taken economic and diplomatic measures off the table."

The document, which was photographed by the freelance photographer Steve Back, said Britain should:

• Push the "UN secretary general Ban [Ki-moon] to take the lead in calling and creating a forum for engaging Russia on Ukraine".

• Accept an emergency summit of EU leaders to discuss Ukraine.

This summit will now be held in Brussels on Thursday.

Government officials said no decisions were made at the NSC meeting, but they confirmed that the call in the document for London's financial centre to remain open to Russians reflected the government's thinking that it wanted to target action against Moscow and not damage British interests.

The prime minister told the NSC the government may be prepared to support EU sanctions that targeted Russian businesspeople seeking to visit the EU. There could also be a "dialling down" of economic co-operation.

Downing Street made clear that diplomatic and economic action would need to be taken to punish Russia. But it did not want to give Moscow an excuse to refuse to talk to Ukraine and the EU.The prime minister said after the NSC meeting: "What we want to see is a de-escalation rather than a continuation down the path that the Russian government has taken, violating the sovereignty and territorial integrity of another country."

He agreed in separate phone calls with his French and German counterparts, François Hollande and Angela Merkel, on Monday night that the international community should speak with one voice on Ukraine as it tells Russia that its actions are "completely unacceptable".